1. Field of the Invention
The present invention relates to a plasma processing apparatus, and more specifically, to a plasma processing apparatus and plasma processing method capable of improving the accuracy and performance of the plasma processing performed to the processing substrate.
2. Description of the Related Art
Generally, a plasma processing apparatus, especially a plasma etching apparatus, improves the performance and accuracy of the plasma processing by applying a high-frequency bias potential or bias voltage to the processing substrate and controlling the energy of ions in the plasma.
Furthermore, since the temperature of the processing substrate also influences the quality of plasma processing greatly, it is important to improve the temperature controllability of the processing substrate. In correspondence thereto, many apparatuses adopt a structure for performing highly accurate temperature control of the processing substrate by electrostatically attracting the processing substrate onto a substrate electrode and providing a temperature controlling gas between the processing substrate and the substrate electrode.
One type of plasma processing apparatus adopting the above-mentioned prior art is the plasma etching apparatus. In a plasma etching apparatus, plasma is generated in a processing chamber within the plasma etching apparatus, and high-frequency bias potential is provided via a structure mentioned earlier (hereinafter called electrostatic chuck) capable of attracting the processing substrate electrostatically to draw the ions in the plasma toward the processing substrate. One example of such apparatus is disclosed in Japanese Patent Application Laid-Open Publication No. 2004-193564 (patent document 1).
Though the art disclosed in patent document 1 refers to utilizing the current and voltage of the processing substrate or the computed values thereof in order to monitor the voltage waveform applied to the processing substrate, it does not teach sufficiently how to compute the voltage waveform of the processing substrate based on the monitored values. Therefore, it was actually difficult to control the voltage of the processing substrate to achieve a desired waveform.
In an electrostatic chuck, since a DC-like high voltage must be applied to the electrode within the electrostatic chuck, it was impossible to measure the bias potential applied to the processing substrate directly, and only the voltage of the electrostatic chuck mechanism or the output power and reflecting power of the bias power supply were measured. The above-mentioned prior art had a drawback in that since there is no sufficient means for measuring the bias potential applied to the processing substrate, the controllability of the bias potential was not good. Thus, there were cases in which the accuracy and quality of the plasma etching process performed to the processing substrate were not improved sufficiently.